High torque motors are practically just a regular, internally commutated brushless DC Motors mounted with additional gear mechanism on top, to either increase the torque or to reduce the RPM (Revolutions per minute). These DC motors are quite powerful and can be used in several hobbyist and industrial application, also one of the standard motors for most of the robot chassis. We are going to use these motors for our tutorial robots.Similarly reducing the RPM while maintaining high torque would require adding up more complex gear mechanism hence the cost of these High torque DC motors mostly depends on the RPM, torque and quality of the motors.The motor shaft from the base motor though a transmission connects the small gear box fixed at its front portion, which in turn generates the necessary torque while keeping the RPM low, the entire gears and gear heads are doped with thick viscous grease lubricant. For more info www.ttmotor.com Thanks.